matrixBlend does not set defaultValue

[liudger]

If the default value is not set for the attributes matrix blend creates the rig will break when you reset the controls.

[miquelcampos]

Sorry, I am don understand. Can you elaborate a little more on the explanation? Thanks

[liudger]

add defaultValue when creating matrix blend #76.

When creating this matrixblend. The default value is not set and when resetting all controls the value will be 0 and the constrain is not working.